Sensor and Performance

The Scimitar RGB Elite is equipped with the PixArt PMW3391. The PMW3391 is basically a PMW3389 with a custom SROM that allows for higher maximum CPI as well as more granular CPI adjustment. According to specifications, the 3391 is capable of up to 18,000 CPI, as well as a maximum tracking speed of 400 IPS, which equals 10.16 m/s. Out of the box, five pre-defined CPI steps are available: 800, 1500, 3000, 6000, and 9000 CPI.

CPI Accuracy

"CPI" (short for counts per inch) describes the amount of counts registered by the mouse if it is moved exactly one inch. There are several factors (firmware, mounting height of the sensor not meeting specifications, mouse feet thickness, mousing surface, among others) which may contribute to nominal CPI not matching actual CPI. It is impossible to always achieve a perfect match, but ideally, nominal and actual CPI should differ as little as possible. In this test I'm determining whether this is the case or not. However, please keep in mind that said variance will still vary from unit to unit, so your mileage may vary.


I've restricted my testing to the four most common CPI steps, which are 400, 800, 1600, and 3200. As you can see, deviation is large (but mostly consistent), which is a below average result. I've used values of 400/800/1550/3050 for my testing to account for the measured deviation.

Motion Delay

"Motion delay" encompasses all kinds of sensor lag. Any further sources of input delay will not be recorded in this test. The main thing I'll be looking for in this test is sensor smoothing, which describes an averaging of motion data across several capture frames in order to reduce jitter at higher CPI values, increasing motion delay along with it. The goal here is to have as little smoothing as possible. As there is no way to accurately measure motion delay absolutely, it can only be done by comparison with a control subject that has been determined to have the lowest possible motion delay. In this case the control subject is a G403, whose 3366 has no visible smoothing across the entire CPI range.


Typically, the xCount test would be used to quickly gauge whether there is any smoothing, which would be indicated by any "kinks" showing up. Weirdly enough, the 3391 in the Scimitar RGB Elite already shows such kinks at 400 CPI, where no smoothing would be expected. Hence, we have to move on to the next test to determine sensor motion delay. As an aside, we can see that SPI timing has periodic jitter.


Here, I'm looking at xSum plots generated at 400, 3200, and 18,000 CPI. The line further to the left denotes the sensor with less motion delay. At 400 CPI, motion delay is identical; at 3200 CPI, motion delay is roughly 5 ms; and at 18,000 CPI, motion delay is roughly 16 ms. This is in line with what to expect from a 3389, which the 3391 is based on. The smoothing kicks in at a higher CPI step, though. That is, at and above 2100 CPI, 32 frames of smoothing are applied, which is then doubled both at 6500 CPI and 12,100 CPI.

Speed-Related Accuracy Variance (SRAV)

What people typically mean when they talk about "acceleration" is speed-related accuracy variance (or short SRAV). It's not about the mouse having a set amount of inherent positive or negative acceleration, but about the cursor not traveling the same distance if the mouse is moved the same physical distance at different speeds. The easiest way to test this is by comparison with a control subject that is known to have very low SRAV, which in this case is the G403. As you can see from the plot, no displacement between the two cursor paths can be observed, which confirms that SRAV is very low.

Perfect Control Speed

Perfect Control Speed (or PCS for short) is the maximum speed up to which the mouse and its sensor can be moved without the sensor malfunctioning in any way. I've only managed to hit just below 4 m/s (which is within the proclaimed PCS range), at which speed no sign of the sensor malfunctioning can be observed.

Polling Rate Stability

All four possible settings (125 Hz, 250 Hz, 500 Hz, and 1000 Hz) look nice and stable.

Paint Test

This test is used to indicate any potential issues with angle snapping (non-native straightening of linear motion) and jitter, along with any sensor lens rattle. This time around I'm testing the highest CPI values of their respective smoothing ranges, which are 6400, 12000, and 18,000 CPI, along with the 400 CPI step. As you can see, no issues with angle snapping can be observed at any CPI step. No jitter is visible at 400 CPI. Although the three latter steps show above average jitter, the degree is still acceptable, especially considering the fact that these represent the worst case of their respective smoothing range. 18,000 CPI, on the other hand, shows excessive jitter. Lastly, very minor sensor lens rattle can be observed, barely enough to register any movement.

Lift-off Distance

The Scimitar RGB Elite offers three pre-defined LOD settings to choose from, as well as the option to perform a manual surface calibration. Using the "Low" setting, the sensor does not track at a height of 1 DVD. Using the "Middle" setting, the sensor does track at a height of 1 DVD, but not at a height of 2 DVDs. Using the "High" setting, the sensor does track at a height of 2 DVDs, but not at a height of 3 DVDs. However, it should be kept in mind that LOD may vary slightly depending on the mousing surface (pad) it is being used on.

Click Latency

Since mechanical switches are being used for the buttons in most computer mice, debouncing is required in order to avoid unintended double clicks. Debouncing typically adds a delay (along with any potential processing delay), which shall be referred to as click latency. As there is no way to measure said delay directly, it has to be done by comparing it to a control subject, which in this case is the Logitech G203. Click latency has been measured to be roughly +5.9 ms when compared to the SteelSeries Ikari, which is considered as the baseline with 0 ms. Please keep in mind that the measured value is not the absolute click latency. Comparison data comes from this thread as well as my own testing, using qsxcv's program.